Sh*t running cooper MPI
Turbo Mini Forums

One of my friends has one of these giving him a lot of shit. Its running piss pooly, cutting out at junctions, sounds like its missing, not pulling well and when it stalls suffers laboured cranking as if the timing is a mile out. He has had it on the diagnostics, but nothing showed, checked compression, and looks healthy. Im worried its goona be one of those arsehole faults to find. Currently have checked and cleaned earth terminals, just incase (although not attempted to run as its getting late). Just after a few thought off any one on here with a bit of experience with these?
Many thanks in advance
Shane

Hit and miss cranking and general poor runing could indicate a problem with either the cam sensor or the coolant temp sensor

Edited by Sprocket on 5th Aug, 2009.

Has he done anything with it recently? Sounds like a problem i had with one, turned out id not plugged something in.

It was the wire that connects the throttle body to the ecu, basically it sits underneath the carb/throttlebody.

My be worth a gander.

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I doubt that the diagnostics 'did not' show anything. It would have shown the operating parameters of the engine, it is then down to the person looking at those to decide where the problem lies. Take it to some one who knows what they are doing

Colin, Im only going on what I was told! The only thing he has done is abuse it. The car has had a history of poor running, and stalling, all be it intermitantly, this time tho its back with a vengance.
Cheers
Shane

I would start with checking the connections to all the sensors for damage/wear/dirt then look at the sensors that colin mentioned earlier.

Coolant sensor is a common one. I had an SPi with a dodgy coolant sensor, resulting in poor running and a crap idle.

Right then, the car is currently seeking shelter in my garage, had some time this afternoon and have been having a bit of a fudge round.
Firstly, checked all connections to sensors and all seemed ok, dry and corrosion free. After to chatting with Dave a little more about it, he said that when it was on diagnostics it did actually show faults with cooling temp, inlet temp, and oil temp sensors. A bit odd that they all showed faults? looking at the diagram it shows they all have a common earth that returns to the ecu, metered this out and found nothing wrong, checked all the other wires from sensors back to the ecu, agin no problems.
I noticed when we started the car the rad fan ran very early on in the warm up, which is leading me to to think U/S sender but I fear it is more than this alone. With regards to testing these with a meter, should they have a resistance that increases with temp? If so does anyone know where I can find what value it should be at a certain temp? Same question with regards to the inlet temp sender. Could someone also explain the testing of the TPS is this just a petentiometer that the resistance value adjusts according to position?
Any other suggestions greatly welcome.
Cheers in advance.
Shane

Cooling fan operation early, or all the time is usualy down to the coolant temp sensor and its wiring. The early MPi's suffered with a short wiring loom for the coolant temp sensor wich tugged the wires at the connnector, this was one of the recall items, and they fixed it with a short fly lead with the apropriate connectors.

The TPS should give aproximate 4.5 to 5v at full throttle and apxroximate 0.2 to 0.4v closed throttle. Its purpose is only to determine throttle rate to compensate for transient fueling. If the throttle if depressed quickly and the engine faulters then recovers, the TPS could be a possable problem.

The stepper motor could be sticking which could cause the stalling issue at junctions, it could also be out of tune, which needs resetting with the diagnostic.

MAP sensors on MPis can still suffer with fuel logging, which results in similar driveability symptoms.

Starting issues I recon are down to the coolant temp sensor

The Air temp sensor doesnt really affect things so much and the adaptive parameters normaly compensate for its inaccuracy. That is not to say that if it has totaly failed, that it wont cause a problem.

I would get it hooked back up to a diagnostic and look at the coolant, air and oil temps then actualy measure them with a digital thermometer. anything over 5 degrees difference is suspect and anything over 10 degrees needs replacing. Take into consideration the innacuracies of measuring the temps on the outer surfaces. Oh and dont forget to check the lambda sensor os functioning, easier to post a link than type it out all over again http://www.theminiforum.co.uk/forums/index...showtopic=67277

THEN, I would check that position of the stepper motor. At idle, Ignition advance should be around 15 degrees +-5 with a stapper position around 40.

Crank shaft sensor issues will also cause starting problems, possibly a 50/50 chance of the engine starting.

The MPi's are the devils work without the diagnostic and it being used properly, which is half the problem with most of them.

For the price of a coolant temp sensor, change it, They are only about £15. the cam sensors are the same as the later K series crank sensors, which should be available from a good motor factor for about £25 at least. The air temp sensors are a bit more expensive at £40, so make sure you have exhausted other cheaper possabilities first. The oil temp sensor is also not cheap, but looking at the wiring diagrams, it does not feed into the ECU, perhaps an omission on the drawing I dont know.

Change the fuel filter, make sure the plugs are NGK BPR6ES.

Dont forget all the normal mechanical stuff such as compression test, and tappet adjustment.

Don't know what else to say

Edited by Sprocket on 22nd Aug, 2009.

Cheers Colin, thats a bit more of a heads up. Dave is going to pick up a coolant temp sensor on mon, so will wait untill then to go any further.
Cheers
Shane